The present invention relates to a heading detecting apparatus including a heading sensor for sensing the earth's magnetic field to thereby determine the forward heading of a moving object.
Conventionally, it has been the practice that when such a heading detecting apparatus is installed in a vehicle, the magnetic field distortion caused by the remanence or residual magnetism of the vehicle, etc., is compensated for by any externally mounted compensating magnets to thereby accurately detect the vehicle heading.
With the known construction, however, it is necessary to give considerations from various aspects such as the location, number and strength of compensating magnets mounted externally to cancel the magnetic field distortion caused by the remanence of a vehicle, etc., thus complicating the required compensation. Also, the field distortion characteristic varies with different vehicles making it necessary to provide a different compensation for each of the vehicles. Further, measures must be considered to deal with changes in the vehicle field distortion characteristic during use.